1. Field of the Invention
The present application relates generally to sealing a manhole opening against ground water infiltration, and more particularly to an article to rest beneath the manhole cover in the existing opening.
2. Description of Related Art
In many urban areas, the growth and sprawl of towns and cities has decreased the amount of ground surface area which is available for absorbing moisture from rain and snow. Accordingly, this water must be drained off and disposed of through suitable means. In some instances where rainfall is minimal, it is possible to collect this water and dispose of it through the city sewer system. Sewer systems are constructed to accommodate a maximum level of influent to be expected at any one time. As long as the amount of water is minimal, conventional sewer systems may be able to process this without much risk. In areas where rainfall and snowfall is more extreme, conventional sewer systems are not capable of handling the runoff without a gross overdesigning of the system.
A basic fact is that rainfall disposed of through the sewer system has to be processed. Whether the sewer system is designed to accommodate runoff collection or not, the act of processing the runoff costs money. Where moisture is minimal, this cost is not significant. However, where moisture is more prevalent, this cost is non-trivial. Such costs can quickly rise and become a hindrance to city budgets. Therefore, costs associated with processing the moisture through a sewer system is not only costly at the time of building the system but also in the act of processing every gallon that passes through the system. Disadvantages of processing moisture through the sewer system include: higher costs, increased wear and tear on the system, and decreased efficiency to oversize the entire sewer system to accommodate rainfall and sewage.
Some towns or cities have developed a storm drain system to collect and route the moisture away through selected drain systems, away from sewer systems. These have done well but are not completely perfect. Localized flooding still occurs. Additionally, during rainy weather an average manhole in a sanitary sewer system can contribute from 3,000 to 12,000 gallons per day of rainwater to the sewer system for treatment. Although storm drain systems help, they are not enough to avoid the extra costs associated with processing runoff from moisture.
A device is needed that acts to seal or prevent the runoff from entering the manholes. Such a device would act to substantially reduce costs and wear to existing sewer treatment systems. A typical manhole includes a main chamber or barrel section to which the sewer pipes connect. That section is topped with a conical riser upward to a size needed to fit a metal frame for the manhole cover. The metal frame includes an internal lip to support the manhole cover. Water typically passes around the cover because the cover and frame are not sealed.
Many devices have been developed to try and seal manholes to prevent the undesired passing of storm water and other moisture. They can include dishes, bowls, and internally translating sealing sleeves to name a few. Such devices usually become quite complex and involve the reworking and construction of the manhole itself. Such work and cost, given the sheer number of manholes, is undesirable.
It is desirable to have a device that is configured to seal the opening of the manhole and operate with existing manhole frames to avoid the need to reconstruct the manhole assembly. Although some strides have been made, considerable shortcomings remain.
While the system and method of the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the application to the particular embodiment disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the process of the present application as defined by the appended claims.